1. Field of the Invention
The present invention relates to a communication system, a communication method, and a non-transitory computer-readable medium.
2. Description of the Related Art
Conference systems that hold a remote conference between users at remote places through a communication network such as the Internet have been widely used. With the conference system, in a conference room in which one of parties such as attendees that have the remote conference is, images of the conference room of the party in the conference and audio such as remarks thereof are image-captured and collected using a terminal device of the remote conference system. Then, they are converted to digital data and transmitted to a terminal device of the other party. In a conference room of the other party, the images are displayed on a display and the audio is output through a speaker. Thus, known have been techniques of holding a conference between users at remote places in a state close to an actual conference.
In the conference system, firmware (programs and applications) is periodically updated in some cases in order to improve call security performance and operation performance. The following method has been known as a method of updating the program in the conference system. That is, update data and meta information (metadata) are acquired by accessing a server through a network so as to update the program and a program of a version that depends on this program.
Japanese Patent Application Laid-open No. 2006-172472 discloses the following method. The method includes receiving a computing device list for identifying computing devices from which each portion of a plurality of portions can be downloaded and updating software of a computing device that downloads the respective portions from a plurality of computing devices.
Japanese Patent Application Laid-open No. 2012-084118 discloses the following update method. The update method includes determining whether update necessary for a communication device is present, receiving a selection operation whether the update is executed from a user when the update is present, and executing the update when the selection operation for executing the update is made.
In the conventional systems performing update, when network cutoff occurs during downloading or a terminal is powered OFF before downloading is completed, data downloaded partway disappears and download of the data should be restarted from the beginning. This results in the problem of an increased download time. In order to solve this problem, considered is a method in which download data is divided and divided pieces of data are downloaded, and all the divided pieces of data are coupled and updated after being downloaded. This method eliminates the necessity of downloading pieces of data that have been already downloaded again even when the power supply is cut off unintentionally as long as they have been completely downloaded on a basis of the divided data, thereby preventing the download time from being increased.
When the power supply is cut off while the divided data is downloaded, a terminal that can use only a narrow band re-downloads the data with increased frequency, resulting in increase in the download time. When a division size of the download data is made small in order to solve this problem, overhead for downloading the respective pieces of divided data is increased and efficiency becomes worse. In particular, a terminal that can use a broad band has more disadvantages than advantages. Thus, an appropriate divided data size is different depending on usable network bands of the terminals. This arises a problem in that not all the terminals can download data efficiently with a single divided data size.
Therefore, it is desirable to provide a communication system, a communication method, and a non-transitory computer-readable medium capable of updating applications efficiently for any of a plurality of communication devices having different usable communication bands.